A flow cytometer/cell sorter is requested for the use of a group of eleven investigators in two departments, Biology and Biophysics, on The Johns Hopkins Homewood campus. Ongoing projects which would benefit from the use of a sorter cover four main areas: 1) cell surfaces and receptors, 2) gene expression, transfection and somatic cell genetics, 3) chromosome structure and biochemistry and 4) carcinogenesis. The sorter's proposed uses range from the daily preparation of single hepatocytes for analysis of cell adhesion, to development of separation methods for non-parenchymal liver cells (for the study of asialoglycoprotein receptors), to the cloning of hybridomas or of mutant or transfected cells (for biochemical and biophysical studies of lipid metabolism or studies of membrane function). Analytical use of the instrument will range over detection of antigen expression in mouse cells transfected with human genes, receptor binding assays, and energy transfer measurements of distances between molecules on the cell surface. The machine will be supported by user fees. It is expected to be largely used by the group, but as techniques for separation are fully developed, time will be available for use by others on the campus or from nearby institutions.